97% of the world’s water is salt water. That’s bad for humans, whoneed fresh water to survive.
Three percent of Earth’s water is fresh water, but
most of this is either underground or frozen in glaciers.
Fresh surface water accounts for only about a quarter of a percent of the world’s water. Brazil is the country estimated to have the largest supply of fresh water in the world, followed by Russia and Canada.
Rivers often carry more water than they appear. There is sub-surface water that runs through the rocks and gravels that underlie the river, an area called the hyporheic zone. This unseen flow is even sometimes larger than the visible flow!
Salt water can be turned into fresh water through an artificial process called desalination, usually achieved through reverse osmosis. It’s fairly expensive, though, and so not worth it in most cases.
It’s only practical in places that severely lack access to fresh water. The Persian Gulf uses this process more than where else.
